Drier felt



July 2, 1957 I. C. HOFFACKER DRIER FELT 2 Sheets-Sheet 1 Filed March 3, 1954 FIG. 'I.

.5 HHH INVENTOR IRA C. HOFFAOKER ATTORNEYS July 2, 1957 l. c. HOFFACVZKER 2,797,713 DRIER FELT Filed March 3, 1954 '2 Sheets-Sheet 2 FIG. 4. Q I? f FIG- 6.

INVENTOR" IRA c. HIOFFACKER @WXM ATTORNEYS United States Patent Ofifice 2,797,713 Patented July 2, 1957 DRIER FELT Ira C. Hoifacker, Baltimore, Md., assignor to Mount Vernon Mills, Inc., Baltimore, Md., a corporation of Maryland Application March 3, 1954, Serial No. 413,828

6 Claims. (Cl. 139-411) The present invention relates to drier fabrics and more particularly to endless felts used in the manufacture of paper and comparable fibrous materials, wherein a wet mat of pulped material supported on said felt is passed into contact with compacting and drying cylinders or rolls.

The conventional drier felt consists of a two or three plane fabric, the plies of which are united by spaced binder threads. These threads are generally inserted after the individual plies have been woven and accordingly the composite structure does not exhibit unusual strength characteristics. Since the upper plane of the felt is in contact with the paper pulp being processed it is desired that the facing ply of the felt be closely woven to avoid undue marking of the finished paper. It will'at once be obvious lat the close weave of the usual smooth fabric will offer comparatively high resistance to the passage of water and/or water vapor therethrough, thus retarding removal of water from the pulp mat and ultimate drying thereof. The close weave of one ply of the felt also precludes its rapid drying after it has been freed of the paper mat,

These ditficulties require operation of the drier felts at reduced speeds in order that the paper mat may be processed properly. There follows automatically a reduction in production together with a more rapid disintegration of the felts because of their increased exposure times.

Various attempts have been made to open the weave of the individual plies of the drier felts, to incorporate fillers of more absorbent materials therein, and to manipulate the binder warps to impart increased strength to the fabric. The changed designs, however, have been marked by the creation of other disadvantages including increased ease of deformation, decreased wear resistance together with added manufacturing problems.

One object of the present invention is to provide a drier felt embodying substantially straight core warps to serve as the principal load bearing elements with covering, interlaced, retaining and protecting filaments applied thereto.

A second object of the invention is to provide a drier felt wherein a composite surface ply enables an increased protection for the core warps disposed thereunder, such protection being obtained without a deleterious reduction in felt porosity.

A further object of my invention is to provide a reinforced drier felt which retains a high degree of pliability and porosity despite the incorporation therein of an additional lamina in the composite assembly.

Other objects and advantages of the invention will be apparent from the following detailed description of certain preferred embodiments thereof as illustrated in the accompanying drawings, in which the figures, primarily diagrammatic in nature are drawn to an enlarged scale and in which:

Figure 1 is a longitudinal section through a drier felt as contemplated by my invention;

Figure 2 is a longitudinal section through a drier felt embodying a modified arrangement of warp binding;

Figure 3 is a longitudinal section through a drier felt, showing a further modification of warp binding;

Figure 4 is a top plan view of the drier felt shown in Figure 1;

Figure 5 is a top plan view of the felt shown in Figure 2; and

Figure 6 is a top plan view of the felt shown in Figure 3.

Referring to the drawings, a drier felt I as presently contemplated consists of four planes. A base plane 2 is composed of conventional warp filaments 3 and 4 and weft threads 5. A second or principal plane 6 is composed of spaced core warps 7 which are laid parallel and are substantially without crimp. A third plane 8 is formed of the warp filaments 3 and 4 and weft threads 9 together with additional warp filaments 10. The fourth and final plane 12 is composed of the warp filament 10 and weft threads 14 together with an additional warp filament 15. The warp filament 15 may extend into and be a part of the plane 8, as shown in Figure 3.

From the foregoing it will be apparent that planes 2 and 8 are united through the medium of the binding warps 3 and 4, the core warps 7 being held therebetween. Similarly planes 8 and 12 are united through the binding warps 10 and 15. Such interlacing secures the four planes into a unitary felt of superior wear resistant properties.

The weft or filling threads 5, forming a part of plane 2 underlie and extend transversely of the core warps 7 of plane 6. The weft threads 5, which are preferably of cotton or other vegetable material although they may be constituted of a synthetic resinous material such as cellulose acetate, regenerated celluloses, polyamide condensation products, acrylonitrile addition polymers and the like. Asbestos fibers could also be utilized. These threads 5 extend across the entire width of the felt and may be separate or connected at the ends establishing a continuous filament disposed in sinuous fashion throughout the plane 2. The number, denier, and spacing of the threads 5 may be varied within wide limits depending upon the porosity desired Within the plane 2, such porosity regulating the rapidity with which the composite felt dispels absorbed water.

The weft or filling threads 9, forming a part of plane 8 overlie and extend transveresly of the core warps 7. In other respects they are substantially the same as weft threads 5 and preferably are in vertical alignment therewith. In some instances, it might be desirable to form the weft threads 9 of asbestos fiber or other heat resisting material.

The weft threads 14 forming a part of plane 12 are preferably formed of asbestos fiber in order to provide a maximum degree of protection for the interior portions of the felt I while in service. These threads 14 are also, in the preferred form of the invention, in vertical alignment with the weft threads of the other planes.

The binder warp filaments 3 and 4 are generally interlaced or interwoven with alternate weft threads 5 and 9 in planes 2 and 8, thus uniting the two planes and securing therebetween the core warps 7. For most purposes these binder warps may be formed of cotton or other cellulosic material although the use of filaments of other materials is possible. These warps could be composed of asbestos fibers or in the construction shown in Figure 2, the warps 3 could be of asbestos, since they extend into plane 8 where they would be in closer proximity to deteriorating heat, while the warps 4 could be formed of cotton.

Similarly, the binder warp filaments 10 and 15 are interwoven with alternate weft threads 9 and 14 of planes 8 and 12, as best shown in Figure 3. For many purposes, as for example when a more porous felt is required the binder warp filament will be confined to plane 12, passing over and under alternate weft threads 14, as shown in Figures 1 and 2. Weaves of this type have alternate weft threads which may be considered as semi-floating, thus providing a less restricted passage of water through the composite felt. These filaments are in the upper portion of the felt and accordingly should be formed of asbestos fibers. I

The core warp filaments 7 are unwoven but are bound by the weft threads and 9 with the interwoven binder warps 3 and 4. There being no crimping or undulation of these core warps there is a reduced tendency toward stretching in length and contraction in width when the felt is in use. These core warps may be composed of single heavy filaments of cotton or other vegetable or synthetic fiber. If desired, these core warps may be plied or cabled in the customary manner of fabrication of textile filaments where extra-heavy duty products are contemplated. The central location of the core warps 7 in the felt I is highly advantageous. Since they are intended to carry substantially the entire load placed on the felt filaments of superior tensile strength should be employed or the number of such core warps should be increased.

Although the drawings show four binder warps to lie between each pair of core warps, it is to be understood that other arrangements may be employed and the desired pattern is repeated across the full width of the felt. Because of the presence of the core Warps considerable latitude in arrangement of the binder warps and their interweaving with the weft threads is possible. It is, of course, important that the upper plane 12 exhibit a smooth top surface in order that the paper mat produced thereon will not be marked. Additional binding warps 15 may be provided for the upper plane 12 for such purpose.

' It will be obvious to those skilled in the art that various changes in the materials and in the arrangement of the several component elements of my drier felt may be made without departing from the spirit or scope of the invention as expressed in the following claims.

What I claim is:

1. A drier felt comprising a multiple plane fabric, the outer plies of which are connected to an intermediate ply by a plurality of binding warps passed above and below selected, spaced wefts of said intermediate ply, the intervening wefts of said intermediate ply being free of similar restricting binding, and having a layer of unwoven core warps, arranged in spaced parallel relation extending longitudinally of said fabric, bound between an outer ply and the intermediate ply of the fabric.

2. A drier felt as defined in claim 1 in which at least one binding warp is passed above and below the alternate wefts of an outer ply only of the fabric.

3. A drier felt as defined in claim l'in which the weft elements of one of said outer plies are formed of asbestos fibers.

4. A drier felt comprising a multiple plane porous fabric, having at least three individual plies which are integrated by a plurality of binding warps interlaced in regular repeated sequence between selected spaced wefts of adjoining planes, each of said binding warps interlacing the weft threads of one outer ply only, with the weft threads of an interior ply, with a layer of unwoven uncrimped, load bearing core warps, arranged in spaced parallel relation extending longitudinally of said fabric and disposed beneath at least two covering plies.

5. A drier felt as defined in claim 4 in which the weft elements of one of said outer plies are formed of asbestos fibers.

6. A drier felt as defined in claim 4 in which the weft elements of one of said outer plies and the binding warps interlaced therewith are formed of asbestos fibers.

References Cited in the file of this patent UNITED STATES PATENTS 

